Auto merge of #861 - RalfJung:rustup, r=RalfJung
Auto merge of #861 - RalfJung:rustup, r=RalfJung

bump Rust (no changes needed)

This is mostly to confirm that this still all works fine.

rust-lang/miri,rust-lang/miri,rust-lang/miri,tsion/miri,rust-lang/miri